Java中的 ByteBuffer compareTo() 方法及示例

Java.nio.ByteBuffer类的compareTo()方法用于将一个缓冲区与另一个缓冲区进行比较。
通过按字典顺序比较它们的剩余元素序列来比较两个字节缓冲区，而不考虑每个序列在其相应缓冲区中的起始位置。就像通过调用 Byte.compare(byte, byte) 来比较字节元素对。
字节缓冲区无法与任何其他类型的对象进行比较。
句法 ：

public int compareTo(ByteBuffer that)

参数：此方法将 ByteBuffer 对象作为参数，与此缓冲区进行比较。
返回值：此方法返回负整数、零或正整数，因为此缓冲区小于、等于或大于给定缓冲区。
以下是说明compareTo()方法的示例：
示例 1：当两个 ByteBuffer 相等时。

Java

// Java program to demonstrate
// compareTo() method
 
import java.nio.*;
import java.util.*;
 
public class GFG {
 
    public static void main(String[] args)
    {
 
        // Declaring the capacity of the bb
        int capacity1 = 3;
 
        // Creating the ByteBuffer
        try {
 
            // creating object of ByteBuffer bb
            // and allocating size capacity
            ByteBuffer bb = ByteBuffer.allocate(capacity1);
 
            // putting the byte to int typecast value in bb
            bb.put((byte)20);
            bb.put((byte)30);
            bb.put((byte)40);
 
            // rewind the  ByteBuffer
            bb.rewind();
 
            // print the  ByteBuffer
            System.out.println("ByteBuffer bb: "
                               + Arrays.toString(bb.array()));
 
            // creating object of  ByteBuffer bb1
            // and allocating size capacity
            ByteBuffer bb1 = ByteBuffer.allocate(capacity1);
 
            // putting the value in fb1
            bb1.put((byte)20);
            bb1.put((byte)30);
            bb1.put((byte)40);
 
            // rewind the ByteBuffer
            bb1.rewind();
 
            // print the ByteBuffer
            System.out.println("ByteBuffer bb1: "
                               + Arrays.toString(bb1.array()));
 
            // compare both buffer and store the value into integer
            int i = bb.compareTo(bb1);
 
            // if else condition
            if (i == 0)
                System.out.println("\nboth buffer are lexicographically equal");
            else if (i >= 0)
                System.out.println("\nbb is lexicographically greater than bb1");
            else
                System.out.println("\nbb is lexicographically less than bb1");
        }
 
        catch (IllegalArgumentException e) {
            System.out.println("Exception throws : " + e);
        }
 
        catch (ReadOnlyBufferException e) {
            System.out.println("Exception throws : " + e);
        }
    }
}

输出：

ByteBuffer bb: [20, 30, 40]
ByteBuffer bb1: [20, 30, 40]

both buffer are lexicographically equal

例子2：当这个ByteBuffer大于传递的ByteBuffer时

Java

// Java program to demonstrate
// compareTo() method
 
import java.nio.*;
import java.util.*;
 
public class GFG {
 
    public static void main(String[] args)
    {
 
        // Declaring the capacity of the bb
        int capacity1 = 3;
 
        // Creating the ByteBuffer
        try {
 
            // creating object of ByteBuffer bb
            // and allocating size capacity
            ByteBuffer bb = ByteBuffer.allocate(capacity1);
 
            // putting the byte to int typecast value in bb
            bb.put((byte)30);
            bb.put((byte)30);
            bb.put((byte)40);
 
            // rewind the  ByteBuffer
            bb.rewind();
 
            // print the  ByteBuffer
            System.out.println("ByteBuffer bb: "
                               + Arrays.toString(bb.array()));
 
            // creating object of  ByteBuffer bb1
            // and allocating size capacity
            ByteBuffer bb1 = ByteBuffer.allocate(capacity1);
 
            // putting the value in bb1
            bb1.put((byte)20);
            bb1.put((byte)30);
            bb1.put((byte)40);
 
            // rewind the ByteBuffer
            bb1.rewind();
 
            // print the ByteBuffer
            System.out.println("ByteBuffer bb1: "
                               + Arrays.toString(bb1.array()));
 
            // compare both buffer and store the value into integer
            int i = bb.compareTo(bb1);
 
            // if else condition
            if (i == 0)
                System.out.println("\nboth buffer are lexicographically equal");
            else if (i >= 0)
                System.out.println("\nbb is lexicographically greater than bb1");
            else
                System.out.println("\nbb is lexicographically less than bb1");
        }
 
        catch (IllegalArgumentException e) {
            System.out.println("Exception throws : " + e);
        }
 
        catch (ReadOnlyBufferException e) {
            System.out.println("Exception throws : " + e);
        }
    }
}

输出：

ByteBuffer bb: [30, 30, 40]
ByteBuffer bb1: [20, 30, 40]

bb is lexicographically greater than bb1

示例 3：当这个 ByteBuffer 小于传递的 ByteBuffer

Java

// Java program to demonstrate
// compareTo() method
 
import java.nio.*;
import java.util.*;
 
public class GFG {
 
    public static void main(String[] args)
    {
 
        // Declaring the capacity of the bb
        int capacity1 = 3;
 
        // Creating the ByteBuffer
        try {
 
            // creating object of ByteBuffer bb
            // and allocating size capacity
            ByteBuffer bb = ByteBuffer.allocate(capacity1);
 
            // putting the byte to int typecast value in bb
            bb.put((byte)20);
            bb.put((byte)30);
            bb.put((byte)40);
 
            // rewind the  ByteBuffer
            bb.rewind();
 
            // print the  ByteBuffer
            System.out.println("ByteBuffer bb: "
                               + Arrays.toString(bb.array()));
 
            // creating object of  ByteBuffer bb1
            // and allocating size capacity
            ByteBuffer bb1 = ByteBuffer.allocate(capacity1);
 
            // putting the value in fb1
            bb1.put((byte)40);
            bb1.put((byte)30);
            bb1.put((byte)40);
 
            // rewind the ByteBuffer
            bb1.rewind();
 
            // print the ByteBuffer
            System.out.println("ByteBuffer bb1: "
                               + Arrays.toString(bb1.array()));
 
            // compare both buffer and store the value into integer
            int i = bb.compareTo(bb1);
 
            // if else condition
            if (i == 0)
                System.out.println("\nboth buffer are lexicographically equal");
            else if (i >= 0)
                System.out.println("\nbb is lexicographically greater than bb1");
            else
                System.out.println("\nbb is lexicographically less than bb1");
        }
 
        catch (IllegalArgumentException e) {
            System.out.println("Exception throws : " + e);
        }
 
        catch (ReadOnlyBufferException e) {
            System.out.println("Exception throws : " + e);
        }
    }
}

输出：

ByteBuffer bb: [20, 30, 40]
ByteBuffer bb1: [40, 30, 40]

bb is lexicographically less than bb1